I have my sons old toy truck which is not remote controlled. it has preprogrammed movements which are initiated through buttons on the cab. it plays music(i already chopped the speaker to mute it) and only goes forward and reverse and has a bunch of leds lighting up. So the board has a single chip http://www.elite-ent.com.hk/upload/090603120608EMD811_&_812.2009.pdf a single cap, 3 transistors of which 2 have the leds hooked up. and some resistors. and then it has a vertical board with abut 13 pins into a small black "mound". im guessing this is where the programming is located? I tried poking around with a voltmeter and found that of the 13 pins, 5 of which are grouped closer to one side have 2 pins which pulse when the wheels are in action. no current on the other 3. but the remaining pins all show roughly 4.5 volts steady even when no action is happening. I was hoping to try to incorporate the motor and circuit with the arduino and some sensors as a first "robot style" project and was hoping maybe someone could give me an idea of finding the right way to be able to bypass the built in stuff and pwm this motor myself with the arduino. My main goal is trying to grasp the basics of circuitry without the aid of an oscilloscope. All of the kit projects were fun to learn, but im finding it difficult to apply any of that to reverse engineering stuff. I hope this all makes sense. And i did quite a bit of searching before posting this.

Hi im in the same situation been teaching myself.As you can see by the data sheet all that chip is doing is Controlling the motors. Apply voltage through the resistorCircuit which I presume will be from your seperate board.If you dont want to buy a scope as they are pricey. Use an Arduino hope that helps a bit